The present invention relates to shearing and is primarily concerned with shearing elongated, metal bodies into billets which are to be extruded.
The shearing of an elongated, generally cylindrical body of aluminum (usually called a log) into billets is effected by passing a portion of the log through a pair of aligned, juxtaposed dies and then causing relative movement of the dies in a direction perpendicular to the length of the log. Because difficulties have been experienced in passing the log through aligned dies, it has been proposed in U.S. Pat. No. 4,152,959 issued May 8, 1979 to F. W. Elhaus to use a die which is formed in two relatively movable parts. In U.S. Pat. No. 4,063,483 issued Dec. 20, 1977 to Kawaguchi et al, there is disclosed apparatus comprising two juxtaposed dies, each of which can be opened by pivoting an upper die part away from a corresponding lower die part.
In use of the apparatus disclosed in the Elhaus patent and in use of the apparatus disclosed in the Kawaguchi et al patent, the dies are expanded by movement of the die parts away from each other to facilitate movement of the logs through the dies and the dies are then contracted, prior to shearing. These prior proposals facilitate movement of a log through the dies and would be satisfactory, if all logs had exactly the same diameter. However, there is variation in the diameter of logs which have the same nominal diameter. If a die is constructed to close when it contains a log having a larger diameter, there will be a clearance between the die and a smaller diameter log having the same nominal diameter. The clearance which then exists permits movement of the smaller log relative to the die during shearing so that a coaxial relation between the log and the die is not maintained. One consequence of this is that the sheared face of the log may not be at right angles to the longitudinal axis of the log. The log may suffer deformation or other damage or may damage the equipment if the log is permitted to move in the die during shearing.